Auto-numbering of measurements in digital multimeter

ABSTRACT

A digital multimeter stores multiple sequential measurements of physical or electrical parameters. Each of the sequential measurements has a name including an automatically generated descriptor. The descriptor for each sequential measurement may indicate a relative position of the measurement within the sequence. For instance, the descriptor may indicate whether the measurement was obtained before or after other measurements in the sequence.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/838,879, filed on Aug. 14, 2008, the disclosure of which ishereby incorporated in its entirety. This application claims priorityunder 35 U.S.C. § 120 to U.S. patent application Ser. No. 11/838,879.

BACKGROUND

Multimeters are used for measuring a variety of electrical and physicalparameters. A multimeter may be a handheld device used for basicfaultfinding and field service work, or a sophisticated bench instrumentcapable of measuring with a high degree of accuracy. A multimeter maydisplay information using any of several different types of displays,such as analog indicators deflected by electrical fields, or digitaldisplays including liquid crystal display (LCD) screens.

Some digital multimeters enable a user to save measurements for laterretrieval and analysis. As an example, some digital multimeters allow auser to save a measurement by actuating one or more buttons or switcheson a multimeter interface. Additionally, some modern digital multimetersinclude a hold function that freezes a displayed value once a stablemeasurement is captured. A user can initiate the hold function, e.g., bypressing a button before taking a measurement and then pressing thebutton once more to release the display. In addition to these save andhold functions, modern digital multimeters may include several otherfeatures for allowing users to capture, view, manipulate, and analyzemeasurement data.

Notwithstanding the large number of features included in many moderndigital multimeters, improvements in both hardware and software areneeded to allow users to more effectively record, organize, and analyzemeasurement information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a front face of a digital multimeter in accordancewith one embodiment.

FIG. 2 illustrates various functional components of a digital multimeterin accordance with an embodiment.

FIG. 3 illustrates an example screen displayed during a HOLD mode inaccordance with one embodiment.

FIG. 4 illustrates an example screen displayed during an AutoHOLD modein accordance with one embodiment.

FIG. 5 illustrates an example screen displayed after an AutoSAVEfunction has been initiated in accordance with one embodiment.

FIG. 6 illustrates an example screen displayed after a first measurementof a sequence has been taken while the AutoSAVE function is active.

FIG. 7 illustrates an example screen displayed in response to selectionof a Review function from the screen of FIG. 6.

FIG. 8 illustrates an example screen displayed in response to selectionof a Replace function from the screen of FIG. 7.

FIG. 9 illustrates an example screen displaying a live multimeterreading in accordance with one embodiment.

FIG. 10 illustrates an example screen displayed after a user hasselected a Save function from the screen of FIG. 9.

FIG. 11 illustrates an example screen displaying a list of names afterthe user has selected a +Name function from one of the respectivescreens of FIG. 10 or FIG. 5.

FIG. 12 illustrates an example screen displayed after a user hasselected a Save function from the screen of FIG. 11.

FIG. 13 illustrates an example screen displayed after a measurementshown in FIG. 12 has been saved.

FIG. 14 illustrates an example screen displayed after a user hasselected the Save function from the screen of FIG. 13.

FIG. 15 illustrates a list of names displayed after a user has selectedthe +Name function subsequent to recording two multimeter readings underthe name “Room”.

FIG. 16 illustrates the list of names shown in FIG. 15 after anauto-incrementing number for the name “Room” has been reset.

FIG. 17 illustrates an example screen including a character palette forediting names for a list such as that illustrated in FIG. 16.

FIG. 18 illustrates an example screen having a menu for modifying athreshold for AutoHOLD and event recording functions.

FIG. 19 illustrates an example screen in which the threshold for theAutoHOLD and event recording functions can be edited.

FIG. 20 illustrates an example configuration of processors for a digitalmultimeter in accordance with an embodiment.

DETAILED DESCRIPTION

Various embodiments of a novel digital multimeter and methods foroperating the same are disclosed. The multimeter may be used formeasuring a variety of electrical parameters associated with electricalcircuitry, such as currents, voltages, resistances and capacitances, aswell as physical parameters, such as temperature. In a typicalembodiment, the digital multimeter includes input/output (IO) featuressuch as a rotary switch, a series of keys and buttons, and a digitaldisplay. These IO features, together with corresponding data capture anddata processing functions, enable users to interact more effectivelywith the digital multimeter relative to conventional multimeters. Moreparticularly, the features of the digital multimeter provide significantimprovements in ease of use, speed of user operation, and safety. Themodifications, alterations, and additions to conventional multimetersthat were necessary to accomplish the features of the inventive digitalmultimeter resulted in benefits that otherwise would not have beenforeseen or appreciated by those skilled in the art at the time of theinvention.

In one embodiment, a digital multimeter with novel improved recordingfunctionality, intelligent storage, minimum/maximum features, datacompression and methods of designing and using the same is disclosed.The digital multimeter has a measurement component for receivingmeasurement data corresponding to one or more physical or electricalparameters, a user interface for receiving user input to place thedigital multimeter into a recording mode, a memory component for storingdata captured by the digital multimeter, and a recording component forautomatically and successively capturing and storing in the memorycomponent a plurality of measurements over a period of time. Therecording component captures and stores each measurement upon detectingthat the measurement has a value greater than an upper recordingthreshold or a value lesser than a lower recording threshold. In thisway, the multimeter may capture the minimum and maximum values during agiven use period. The other values may be stored or discarded by themultimeter and can be controlled via user input. For example, a usercould specify that only the five highest and five lowest values be savedand recorded during a given usage period. A “Peak/CF” function providesa direct peak measurement and calculated crest factor (“CF”) using peakand rms (calculated as peak divided by root mean square). Crest factoris a measure of signal distortion. Any of the functions of themultimeter can be determined by pressing the “i” button (informationbutton) on the multimeter.

The recording mode operates in several ways. One manner of operation ofthe recording component is when the lower recording threshold is apreviously recorded minimum measurement value. The upper recordingthreshold may be a previously recorded maximum measurement valuecaptured by the multimeter or may be manually or automatically inputinto the multimeter. Likewise, the lower recording threshold may be apreviously recorded or user input minimum measurement value. The periodof time over which the measurements are taken or input is gathered isany period of time in which the multimeter is in use and is eithercontrolled by the user or automatically controlled. For example, aperiod of time may be the time that the multimeter has been powered upduring a given session of use. It may also be a defined period of time,such as an hour, a day or a week. In one embodiment, the upper and lowerrecording thresholds are stable measurements, which are measurementstaken by the multimeter that fluctuate within predetermined limits thatare either default limits or limits set by the user. The lower recordingthreshold and/or upper recording threshold may have a fixed valueestablished prior to the period of time. The multimeter input componentthat allows a user to enter or edit the lower recording threshold and/orthe upper recording threshold may be through the multimeter functionmode buttons, through the display function, may interact using both, ormay be plugged in to an external computer or keyboard to enter usercommands recognized by the multimeter.

The digital multimeter optionally has additional features including afeature wherein the lower recording threshold and/or the upper recordingthreshold are defined relative to a baseline measurement value. Thebaseline measurement value is either input by the user, selected using aprogram of the multimeter, or selected by the user with assistance froma program of the multimeter. The baseline measurement value may bestatic or it may be fluid over a period of time. For example, thebaseline measurement value may be a previous value captured by themultimeter, such as when the multimeter is programmed to record ameasurement smaller than the previous minimum or larger than theprevious maximum value. For each of these measurements, the mostrecently recorded minimum and maximum values are the baselinemeasurement values, which exist until replaced by a lower minimum orhigher maximum value, which then become the new baseline. Alternatively,the baseline is a fixed value over the period of time.

A multimeter optionally contains a graphical display for indicating whenthe digital multimeter is capturing and storing upper and lowerrecording values, such as a display component for displaying minimum andmaximum values of measurements captured during the period of time. Thedisplay may be programmed to display other values, including median andaverage values, and other values of statistical interest to the user,graphical representations of such values, and other statistical datapertaining to the data captured and stored during the current period oftime and/or previous periods of time. The data may be displayedindividually or in conjunction with other data. Thus, for example, thedisplay component may show the minimum and maximum values ofmeasurements captured during the period of time simultaneously. Thedisplay may show comparisons regarding data captured within and betweenvarious periods of time of use of the multimeter. In one embodiment, thedata is shown in graphical form and a portion of the graph may beenlarged for easier viewing and analysis.

In certain embodiment, when data is recorded, the multimeter emits anaudible indication, such as a beep, ring, or musical tune, to indicatethat such data has been recorded. The user may control this feature,such as turning the audible indicator on or off, associating sounds, orcertain sounds with certain data. For example, the multimeter may beprogrammed to emit a low beep when a new minimum value has been recordedand a high beep when a new maximum value has been recorded during agiven time period. The multimeter may also audibly indicate when it hasbeen turned on or off, when it is nearing a full memory, or any otherindication that the user chooses to be notified of by a sound.Alternatively, the multimeter may have a flashing light, change indisplay screen, or a vibrate mode to indicate the any captured andrecorded value or any other event as described herein.

When recording dynamic data, the lower recording threshold and the upperrecording threshold may vary over successive intervals within the periodof time. The recording component may capture and store at least onemeasurement for each interval. The intervals may be pre-set by a programof the multimeter or may be entered by the user. For example, a usercould program the multimeter to record a maximum and minimum value everyhour (the interval) for a day (the period of time). The data would thenshow 24 maximum readings and 24 minimum readings, one for each hour ofthe day. One option for using the multimeter is that the recordingcomponent stops automatically capturing and storing measurements after apredetermined time interval elapses. In the above example, themultimeter may stop recording and even turn itself off or power downafter the readings for the 24^(th) hour has been recorded. Themultimeter may alternatively be allowed to continue recording until theuser manually terminates the capture and storage of data.

While the lower recording threshold for a particular interval may be aminimum measurement value obtained during the interval and/or the upperrecording threshold for a particular interval may be a maximummeasurement value obtained during the interval, the values may also bevalues other than maximum and minimum values.

If a multimeter is running for a longer period of time, power may be anissue. The multimeter typically has a battery, and may also have anattachment for a power connection to power the multimeter, recharge thebattery, or both. A long-life battery may be used in connection with themultimeter. If the multimeter is in extended use and/or if the memory ofthe multimeter is nearing capacity, the recording component maydown-sample measurements stored in the memory to decrease the amount ofmemory occupied by the measurements. The down-sampling may occur uponthe multimeter detecting that a predetermined amount of memory space hasbeen filled or upon detecting the passage of a predetermined amount oftime. The down-sampling may also occur upon specific user input todown-sample. Similar to down-sampling, the multimeter, or one or morecomponents of the multimeter, may operate at reduced power settings,either by explicit user command or when the multimeter detects thatpower is low and automatically adjusts its power consumption.

In another embodiment, a digital multimeter has novel automatic captureand storage features, related naming and identification features. Thedigital multimeter preferably has a measurement component for receivingmeasurement data corresponding to one or more physical or electricalparameters, a user interface for receiving user input to place thedigital multimeter into an auto-save mode, a memory component forstoring data captured by the digital multimeter, and an auto-savecomponent for automatically capturing and storing data when the digitalmultimeter is in auto-save mode.

The auto-save mode may operate in several ways. One manner of operationof the auto-save mode is by the auto-save mode first detecting when thedigital multimeter receives stable measurement data of one or morephysical or electrical parameters, and then automatically saving stablemeasurement data to the memory component upon making the detection. A“stable measurement” is a measurement taken by the multimeter thatfluctuates within predetermined limits that may be either default limitsor limits set by the user during a discrete time period. For example, auser may determine that a stable measurement is a measurement of voltagethat varies no more than 2 volts over the period of time of 10 seconds.Any predetermined amount or proportion may be set by the user. Anothermanner of operation of the auto-save mode is by the auto-save mode firstdetecting when the digital multimeter receives any measurement data,including data outside of the stable measurement parameters, and thenautomatically saving the measurement data to the memory component uponmaking the detection.

The digital multimeter may have additional features, including agraphical display for indicating when the digital multimeter is inauto-save mode, for displaying one or more real-time measurement valuesderived from the received measurement data recorded in auto-save mode,and/or for indicating a value of each new stable measurement afterdetection by the auto-save component. The graphical display may allowthe user to view and assign a name and/or a number to a particularmeasurement data or a series of measurement data.

In another embodiment, the display shows real-time measurement valuesbased on the received measurement data and has an auto-hold componentfor automatically freezing the value of the stable measurement withinthe display component upon detecting receipt of the stable measurement.A “saving” component feature of the multimeter may save a value that hasbeen frozen within the display in response to a user input submitted viathe user interface component. If the multimeter comprises an audiooutput component, which audibly indicates when a feature is activated ordeactivated, it may be activated when the auto-save component detects anew stable measurement such as by beeping, ringing, or playing music.

The user may be able to set the multimeter to auto-save mode and thenbegin operation in such mode by entering a “start input.” Similarly, theuser may be able to terminate the operation in auto-save mode byentering a “stop input.” If a user wants to replace a value alreadyrecorded by the multimeter, the user may effect a “redo” by actuating aredo-input while the digital multimeter is in the auto-save mode andreplacing a most-recently saved measurement among the sequence ofmeasurements in response to the redo-input. If the user wants to replacea value that was taken more than one value-recorded-input ago, the usercan actuate the replace-input while the digital multimeter is in theauto-save mode and replacing one or more saved measurements within thesequence of measurements in response to the replace-component. For this,the user may use navigation keys to direct the multimeter to the valuein the sequence that will be replaced by the new value. Alternatively,the multimeter allows for values to be deleted and not replaced withother values.

The digital multimeter preferably has a navigation component combinedwith or embodied in the user-interface component that allows the user touse real or virtual arrow keys, a touch screen, cursor or mousemovement, or other methods of moving between, selecting, anddeselecting, various of the functionalities of the multimeter.

In yet another embodiment, a digital multimeter has a novel automaticincrementing feature in relation to data captured and/or saved insequence, an auto-naming feature, auto-incrementing and auto-namingfeatures used in conjunction to create novel alphanumeric identifiers,auto-incrementing features used with manual naming, combinations ofthese and other features. The digital multimeter may have a measurementcomponent for receiving measurement data corresponding to one or morephysical or electrical parameters, a user interface component forreceiving user input to save measurement data and associate one or morenames with the saved data, and an auto-incrementing descriptor componentfor automatically assigning incremented descriptors to the saved data.The saved measurement data may comprise a first data reading associatedwith a name and a first automatically incremented descriptor and asecond data reading associated with the name and a second automaticallyincremented descriptor. The name is typically the same name for morethan one data measurements taken within a sequence, with sequentialauto-descriptors accompanying the name to differentiate themeasurements. For example, if the name is “outdoor,” the first datameasurement reading may be called “outdoor-1” and the second measurementreading “outdoor-2,” and so forth for all the measurements taken in thesequence. The name may also indicate location of or conditions underwhich the reading occurred.

The auto-incrementing descriptor may be used anywhere in conjunctionwith the name, including before the name, after the name, or in themiddle of the name. Preferably, the user will be able to control thelocation of the auto-incremented descriptor. The automaticallyincremented descriptors may indicate the order in which the saved datawas received. The descriptors may be sequential (1, 2, 3, . . . ), evenor odd (2, 4, 6 . . . ), multiples, increasing, decreasing, or any otheridentifying orientation, which may be automated or may be controlled bymanual user input. In various alternatives, the name comprises a stringof alphanumeric characters and an automatically incremented descriptorappended to the string of alphanumeric characters. The automaticallyincremented descriptor may comprise at least one number, letter, symbol,or any combination thereof.

In a related embodiment, the digital multimeter also has a sequencerecording component for saving a sequence of readings in response to aone or more user inputs presented at the user input component. Themultimeter associates each reading among the sequence of readings with aname and the auto-incrementing component automatically assigns anautomatically incremented descriptor to each name associated with thesequence of readings. The user interface component may comprise adisplay element, such as a screen, one or more “soft buttons,” whichfunction can change and which current function or functions is typicallyindicated on the display element.

The names given to the measurement data may be generated from a set ofdefault names stored in a memory within the digital multimeter or anexternal computer attached to the digital multimeter. The names may alsobe provided by the user for a particular measurement or set ofmeasurements. Both default names and manually entered names provided bythe user may be edited in an editing component via the user interfacecomponent. Date, time, and location data regarding the gathering of themeasurements may also be the entire or a portion of theauto-incrementing descriptor. The multimeter optionally has a resetcomponent for resetting values of the automatically incrementeddescriptors. The reset may occur in response to one or more user inputsor may be programmed to occur automatically after a predetermined seriesof events or period of time.

A digital multimeter having an auto-incrementing descriptor may haveadditional components, including a display component and a user inputcomponent. The display component may be used for a displaying any of theinput or output regarding the multimeter, including the measurement datareading and associated name with the auto-incremented descriptor. Thedisplay may show the name assigned to the data automatically or inresponse to a user input, such as a soft key that indicates that thedata name or a series of names be displayed. Soft keys may be used tocorrespond to a variety of user input components and may receive data,which is then displayed on the display component, such as the screen. Auser may manually name the measurement data reading by entering analphanumeric string after the data has been recorded. Manual namingoccurs via the display interface or by any other manner of entering dataor instructions into the multimeter. The names will typically indicatethe order in which the data readings occurred because theauto-incrementing descriptor may increment in ascending order.

In another embodiment, a multimeter is connected to an external centralprocessing unit or computer. The multimeter may be connected to theexternal computer before, during, and/or after use. Transfer of databetween the multimeter and the computer preferably occur both ways. Forexample, the multimeter can be connected to the computer and thecomputer can download a new set of operating instructions to themultimeter. This is a significant advantage because the multimeter canbe updated with new software programs and new versions of existingprograms without having to replace the memory of the multimeter.Conversely, the multimeter can upload saved data from its memory intothe external computer, thus freeing up more space for additionalmeasurements. If the external computer is connected to the multimeterduring use, the processor of the computer and the processor themultimeter can work in tandem to process the data being acquired by themultimeter. The data acquired can then either be saved to the memory ofthe multimeter or the external computer or both. Another featureassociated with an external computer is that image data, including a“screenshot” of the meter display can be taken and uploaded to thecomputer. The screenshot is a graphical file that is a snapshot of themeter's graphical display at a particular point of time. The format ofthe screenshot may be any graphics or image format, such as a JPEG, GIF,or PDF file.

The many embodiments of a digital multimeter described herein may beused alone or in any combination or permutation. For example, amultimeter with automatic capture and storage features can also have anauto-incrementing feature. Similarly, a digital multimeter with an audiooutput notifying feature can also have a display screen and a max/minrecording mode. One skilled in the art will appreciate the variety offeatures for a digital multimeter, which are further described hereinwith respect to the figures.

Description of Digital Multimeter Components

FIG. 1 illustrates a front face of an example multimeter 100. Multimeter100 typically comprises a compact, handheld body, including contourindentations improving suitability for one-handed operation. The face ofmultimeter 100 is generally characterized by a display 105, a rotaryswitch 120, soft keys 110-113, navigation buttons 114-117, dedicatedbuttons 125-128, and various input jacks 121-124. Multimeter 100 can bepowered by AA alkaline batteries or another suitable power supply.

Measurement Functions and Modes

Multimeter 100 contains one or more measurement components, such assensors, for receiving measurement data for detecting physical andelectrical parameters. Multimeter 100 may provide primary measurementfunctions, such as functions for measuring voltage, current,temperature, resistance, electrical continuity, conductance,capacitance, diode test, low impedance, low resistance (e.g., 50 Ohms),and AC/DC combinations (AC+DC, AC,DC). Additionally, multimeter 100 mayfurther provide secondary measurement functions, which are functions formeasuring secondary characteristics of signals or measurements generatedby the primary measurement functions. Examples of secondary measurementfunctions include functions for measuring signal frequency, duty cycle,pulse width, decibels, and crest factor. Multimeter 100 may perform aprimary measurement function simultaneous with performing one or moresecondary measurement functions.

Multimeter 100 may be set to certain modes that operate in conjunctionwith various measurement functions. These modes determine howmeasurements are acquired and represented without changing themeasurement function. Examples of these modes include Min/Max, Hold,Auto Range, Manual Range, Peak, and Record modes. Min/Max mode, whichmay be accessed via the “MIN MAX” button 126, is a mode in whichmultimeter 100 displays minimum, maximum, and average measurements thathave occurred over a period of time. In this mode, whenever a newmaximum or minimum occurs—exceeding the previous maximum or minimum—thenew maximum or minimum is stored and displayed. Hold mode, which may beaccessed via the HOLD button 125, is a mode in which a displayed valueis frozen on the display. Manual Range mode is a mode in which a range,or resolution, of a displayed value is specified by user input. AutoRange mode is a mode in which a range of a displayed value is determinedby the multimeter. Both Auto Range and Manual Range may be accessed viathe RANGE button 127, which allows a user to switch between the twoRange modes. Recording mode is a mode in which a time series ofmeasurements of a single continuous signal are recorded over a period oftime. For example, Recording mode could be employed to measure linevoltage or frequency to determine if the voltage is within appropriatelimits.

User Input Devices—Rotary Switch, Buttons, and Keys

User input components of multimeter 100 include, among other things,rotary switch 120, navigation buttons 114-117, soft keys 110-113,dedicated buttons 125-128, an on/off switch 118 and a backlight controlbutton 119. Dedicated buttons 125-128 (also referred to as dedicatedmode buttons) include an [Info] button 128, a [HOLD] button 125, a [MINMAX] button 126, and a [RANGE] button 127. A user can interact withmultimeter 100 using the various buttons and other features included onthe face of multimeter 100. Additionally, the user's interactions can beguided by information presented on various screens of display 105.Multimeter 100 may further present the user with output via display 105,an indicator light, and/or an audible beeper. Multimeter 100 furtherincludes an internal memory for storing information such as measurementvalues.

Soft keys 110-113 are located in an area beneath the display 105 andpositioned to correspond with labels 106-109 on the display. Pressingone of the soft keys 110-113 invokes the command indicated by thecorresponding label on the display. Every screen shown on display 105has a custom set of soft key labels 106-109. Some screens have fewersoft key labels than soft keys. When a soft key label is left blank, thecorresponding soft key is disabled. For example, in the screen shown inFIG. 1, soft key label 106 is labeled Menu and corresponds to soft key110, soft key label 107 is labeled Save and corresponds to soft key 111,soft key label 109 is labeled Setup and corresponds to soft key 113, andsoft key label 108 is left blank, indicating that soft key 112 isdisabled.

In the example of FIG. 1, navigation buttons 114-117 are centrallylocated among the other buttons of multimeter 100. Navigation buttons114-117 correspond to four cardinal directions: [UP] 115, [DOWN] 117,[LEFT] 114, and [RIGHT] 116. Navigation buttons 114-117 can be used tomove within menus and dialogs and to make choices and perform dataentry. They can also be used to scroll through a sequence of informationtoo extensive to be displayed on a single screen.

[Info] button 128 can provide access to context-sensitive explanatoryinformation about a measurement function and display contents.Additional details regarding [Info] button 128 are discussed furtherbelow. The context-sensitive explanatory information may appear in apop-up information dialog which covers most of the underlying screen.

Multimeter 100 may include a backlight for the display 105 to allowimproved viewing in conditions of reduced light. The backlight istypically activated by backlight control button 119. Multimeter 100 canalso include an On/Off button 118 used to turn multimeter 100 on or off.

Rotary switch 120 includes positions 130, 132, 134, 136, 138, 140, 142,144, 146, and 148. Each of these positions corresponds to at least oneprimary measurement function of multimeter 100. These primarymeasurement functions are indicated by symbols about the periphery ofrotary switch 120. Where more than one symbol is located next to asingle position of rotary switch 120, the symbol closest to rotaryswitch 120 corresponds to a default primary measurement function forthat position and any symbols located farther away from rotary switch120 correspond to non-default primary measurement functions for thatposition. For instance, position 142 of rotary switch 120 corresponds toa default primary measurement function for capacitance measurement(indicated by a capacitance circuit symbol), and a non-default primarymeasurement function for diode testing (indicated by a diode circuitsymbol). A user can change the primary measurement function currentlyassociated with a particular position of rotary switch 120 by actuatingspecific buttons on the face of multimeter 100.

For explanation purposes, the term “active primary measurement function”refers to the primary measurement function currently associated with aparticular position of rotary switch 120. In other words, the activeprimary measurement function for a particular position of rotary switch120 is the function that is performed by multimeter 100 when rotaryswitch 120 is moved to the particular position. As will be appreciated,the active primary measurement function for a particular position ofrotary switch 120 may be a default primary measurement function or anon-default primary measurement function.

As indicated by the various symbols around rotary switch 120, multimeter100 may perform several different primary measurement functions. Theseprimary measurement functions may include, for example, AC voltagemeasurement (e.g., from 0 V to 1000.0 V), AC millivolt measurement(e.g., from 0 mV to 3000.0 mV), DC voltage measurement (e.g., from 0 Vto 1000.0 V), DC millivolt measurement (e.g., from 0 mV to 3000.0 mV),resistance measurement (e.g., from 0Ω to 500.0 MΩ), capacitancemeasurement (e.g., from 0.001 nF to 50 mF), temperature measurement, ACcurrent measurements (e.g., from 0 mA to 20.000 A), AC currentmeasurements (e.g., from 0 μA to 5000.0 μA), DC current measurements(e.g., from 0 mA to 20.000 A), DC current measurements (e.g., from 0 μAto 5000.0 μA).

When rotary switch 120 is set to a particular position, multimeter 100may be set to display a screen containing pertinent information relatedto the present primary measurement function. Each screen may present oneor more menu items related to the present primary measurement function.These menu items may be presented by placing specific names on soft keylabels. Accordingly, a user may select from the menu items by pressingthe corresponding soft keys 110-113. As discussed below with referenceto FIGS. 4 and 5, these menu items may, among other things, allow a userto switch between the different primary measurement functions associatedwith a current position of rotary switch 120.

Dedicated mode buttons 125-128 provide direct single-press access todifferent modes. Pressing [HOLD] button 125 may cause multimeter 100 tohold a currently displayed measurement value. Pressing [MIN MAX] 126button may cause multimeter 100 to capture the highest, lowest, andaverage readings over a period of time. Pressing [RANGE] button 127 maycause multimeter 100 to prompt a user to manually select a desiredmeasurement range. Other modes may be selected by using soft keys110-113 and navigation buttons 115-117 to make selections from menus ondisplay 105.

Multimeter 100 can be turned off and on again without losing its currentsettings. For instance, multimeter 100 can be turned off and on againwithout returning from a non-default primary measurement functionassociated with a particular position of rotary switch 120 to a defaultprimary measurement function associated with the same position.Similarly, multimeter 100 can be turned off and on again withoutreverting from a non-default mode associated with a particular positionof rotary switch 120 to a default mode associated with the sameposition. Moreover, upon powering up, multimeter 100 can resumeperformance of any previously selected secondary measurement functionswithout requiring additional user input. In other words, multimeter 100preserves specific user-configured settings even when turned off. Theuser may configure the meter to defeat this feature, however.

When rotary switch 120 changes from a first position to a secondposition, the screen of display 105 changes in accordance with a newmeasurement function associated with the second position. Typically, anymodes or other configurations that have been designated for the firstposition are not maintained when rotary switch 120 changes to the secondposition. For instance, if multimeter 100 performs a first measurementin Hold mode while rotary switch 120 is at a first position, multimeter100 will not necessarily maintain the Hold mode when rotary switch 120is moved to a second position.

Multimeter 100 may receive input signals through probes or other inputsources connected to input jacks 121-124. Multimeter 100 may produceoutput through display 105 and other output interfaces such as indicatorlights or audio sources for generating a beeping noise. Multimeter 100can include an internal memory 204 for storing information such asmeasurement values.

Multimeter User Display

Display 105 may comprise an LCD screen or any other suitable type ofdisplay. In FIG. 1, rotary switch 120 is set to position 132, whichcorresponds to a voltage measurement for an alternating current; display105 displays voltages measured by this measurement function. As shown inFIG. 1, some measurements are displayed in a bold type and/or in acomparatively larger font size in relation to other displayedmeasurements. Display 105 may further display additional measurements orcollateral information related to the displayed measurements.

Overview of Various Functional Components

FIG. 2 illustrates various functional components of digital multimeter100 in accordance with an embodiment. Referring to FIG. 2, multimeter100 comprises a processor 206 operatively connected to display 105, amemory 204, an internal logical autohold input 208, and an internallogical autosave input 210.

Processor 206 receives inputs from autohold input 208 and autosave input210 to control the operation of an AutoSAVE mode and an AutoHOLD mode.In response to the inputs from autohold input 208 and autosave input210, processor 206 retrieves and stores data in memory 204 in connectionwith an AutoSAVE function and an AutoHOLD function. Additionally,processor 206 controls display 105 to present information to a user inconnection with the AutoSAVE and AutoHOLD functions. The operation ofthe components shown in FIG. 2 is described in further detail below.

AutoSAVE and AutoHOLD

The AutoSAVE function of digital multimeter 100 is designed for storingand displaying a series of stable measurements captured by multimeter100. A user may initiate the AutoSAVE function by actuating a button orswitch on multimeter 100. Thereafter, the user may move the probes ofmultimeter 100 between various contact points on one or more circuits,while multimeter 100 automatically saves different measurements obtainedat the different contact points. The AutoSAVE function saves a user'stime by eliminating the need for the user to provide further input tothe multimeter each time a new measurement is captured. The AutoSAVEfunction also increases accuracy because the user does not have toremember or manually record the previous values, thus reducing anyrecording or reentry errors from the process. In FIG. 2, “autosaveinput” and “autohold input” are internal logical modes of the multimeterand are not themselves external electrical inputs.

Each time the user moves the probes to a new contact point on a circuit,the AutoSAVE function monitors new input signals until the new inputsignals reach a point of equilibrium. In other words, the AutoSAVEfunction determines when new measurements become stable. Upondetermining that a new measurement has become stable, the AutoSAVEfunction triggers a recording of the new measurement. In exemplaryembodiments, the determination that the measurement has become stablecan be made by comparing the rate of change to a default threshold value(e.g., 0.4%), or alternatively, a user-programmed threshold value.

As provided above, detecting that the probes have been moved to a newcontact point can be a triggering event to record a new measurement. Forexample, the digital multimeter 100 can detect an infinite resistanceindicative of an open circuit, and then monitor the input signals for ameasurable resistance to once again begin monitoring for a next point ofequilibrium to record. In some other instances, such as when measuringtemperature is normal, the digital multimeter 100 will begin a nextmeasurement upon detecting that the present measurement value haschanged beyond a certain threshold percentage of the most recentlyrecorded value.

The event threshold may operate on a basic value of the primarymeasurement before the application of any secondary calculations, suchas might produce values such as REL, dB, or CF. According to someembodiments, an event threshold may be applied to a combinedmeasurement, e.g., AC+DC, AC over DC, DC over AC, etc.

AutoHOLD may treat unstable-to-stable transitions as a trigger of thethreshold event. That is to say, a threshold event may be triggered inthe AutoHOLD mode when 1) there is a stable measurement result, 2)subsequent instability occurs for a long enough period for the digitalmultimeter 100 to detect an unstable period, and 3) the next stablereading is within the event threshold of the previous stable reading.

When measuring signals with a very low magnitude, the AutoHOLD eventthreshold percentage may result in an absolute threshold value that isso small that it may cause low-level noise on the signal to generatenumerous automatic updates. For example, 4% of a very small signal maybe more than an order of magnitude smaller and may be in the noiselevel. According to embodiments of the digital multimeter 100, largenumbers of unwanted updates may be avoided by setting a minimumthreshold floor below which low-level signal threshold values will notbe allowed. The value of the floor may be set to detect an open leadscondition for an active function and range. The threshold floor and theopen leads threshold may be two separate values. The threshold floor maybe the value below which an event window is a constant size, whereas theopen leads threshold is the value below which no AutoHOLD updates resultbecause the leads are assumed to be floating.

FIG. 3 illustrates an example screen 300 displayed during a HOLD mode ofmultimeter 100. Screen 300 includes labels 304, 306, and 308respectively corresponding to the AutoHOLD function, a Save function,and the AutoSAVE function. A user can initiate any of these functions bypressing a soft key adjacent to the corresponding label. For explanationpurposes, it will be assumed that soft key 110, which corresponds tolabel 304, acts as the autohold input 208 shown in FIG. 2, and soft key112, which corresponds to label 308, acts as autosave input 210 shown inFIG. 2.

Screen 300 shows a reading 302 that has been frozen on the display bypressing dedicated [HOLD] button 125. Within display 300, an annunciator310 indicates that the HOLD function is active.

In one embodiment, when the multimeter is in a mode that is not alive-measurement mode, the status bar at the top of the screen is“inversed,” meaning that white characters in the status bars turn blackand the black background of the status bars turns white. The status barmay be inversed when the meter is in HOLD, AutoHOLD or AutoSAVE mode,when the user is viewing readings from memory (as opposed to livereadings), and when a recording, Min Max, or Peak session has beenstopped, but has not yet been closed. An inversed status bar is designedto provide the user with a visual reminder that the values on thecentral portion of the display are not live measurement values.

If the user selects the AutoHOLD function by pressing soft key 110,processor 206 will automatically hold every subsequent stable reading ondisplay 105. If the user selects save 306, processor 206 will save tomemory 204 any measurement held on screen 300. If the user selects theAutoSAVE function by pressing soft key 112, processor 206 willautomatically hold subsequent stable readings on display 105 and savethe readings to memory 204. Processor 206 can be programmed to beep orflash the measurement on display 105 each time a new stable measurementis detected during the AutoHOLD or AutoSAVE functions.

FIG. 4 illustrates an example screen 400 displayed when multimeter 100is in the AutoHOLD mode. Screen 400 shows a reading 402 that has beenfrozen on the display by selecting the AutoHOLD function in screen 300.An annunciator 410 displays that the AutoHOLD function is active. Thestatus bar may be inversed in AutoHOLD mode.

Screen 400 includes the labels Cancel, Save 404, AutoSAVE 406, and Setup408. These labels correspond, respectively, to a Cancel function forcanceling the AutoHOLD mode, a Save function for saving the frozenmeasurement, the AutoSAVE function, and a Setup function for modifying aconfiguration of the AutoHOLD function. Where a user selects the Savefunction, processor 206 saves the frozen measurement to memory 204.Where the user selects the AutoSAVE function, processor 206automatically holds subsequent stable readings on display 105 and savesthe stable readings to memory 204.

FIG. 5 illustrates an example screen 500 displayed in multimeter 100after the AutoSAVE function has been initiated. Within screen 500, anannunciator 510 indicates that the AutoSAVE function is active. Thestatus bar may be inversed in AutoSAVE mode. Screen 500 includes labels504, 506, and 508, which respectively correspond to a +Name function, aStart function, and a Cancel function. A user can initiate any of thesefunctions by pressing the corresponding soft key among soft keys 110through 113. The user can name a sequence of measurements to be taken bythe AutoSAVE function by selecting the +Name function and assigning aname for the sequence. Once the name is assigned, the sequence ofmeasurements is performed and the name is used to identify each of themeasurements. As will be explained in further detail with reference toFIG. 10, an automatically incrementing descriptor such as an increasingnumber may be appended to the name to generate names for the successivemeasurements. For instance, a sequence with the name “voltages” mayinclude measurements named “voltage-1”, “voltage-2”, and so on.

When a user selects the Start function in screen FIG. 5, the autoSAVEfunction begins saving a sequence of measurements. The measurements inthe sequence will be named and saved using the most recently used ormost recently entered name. If the same soft key is set to AutoSAVE inscreens 300 and 400 and Start in screen 500, then the user can quicklystart the autoSAVE function by pressing soft key 112 twice from eitherscreen 300 or screen 400. The autoSAVE function can also be activated bypressing dedicated [HOLD] button 125 while in screen 500. If thesequence is activated by pressing [HOLD] button 125, the previouslysaved measurement can be used as the first stable reading. SelectingCancel can cause the display to return to the previous screen in whichthe autosave function was selected. If dedicated [HOLD] button 125 ispressed while the autoSAVE function is in progress, a live measurementvalue can be saved to memory 204 as if it had been detected as a stablevalue and automatically saved. The Manual Range mode may be changedduring execution of the autoSAVE function. The soft keys 110-113 can beset so that the only available soft key function is Cancel after theautoSAVE function has been started, but before the first measurement hasbeen taken and recorded.

FIG. 6 shows an example screen 600 that can appear after the firstmeasurement of a sequence has been taken using the autoSAVE function.Screen 600 includes a relative sequence number 612 reflecting whichincrement within the sequence is shown in the display. As shown in FIG.6, the relative sequence number 612 is the number “3”, which indicatesthat the reading 302 is the third reading in the sequence and themultimeter is waiting for a next stable reading. When one or moremeasurements have been saved, the soft keys can provide for redoing thelast saved reading and reviewing previously saved readings.

In FIG. 6, soft key functions in screen 600 include Stop 604, Redo last606, Review 608, and Cancel 610. Selecting Stop 604 can deactivate theautoSAVE function and return display 105 to the screen shown prior toselecting the autoSAVE function. Selecting Redo last 606 can causerelative sequence number 612 to blink indicating a pending replacement.Once multimeter 100 detects a new stable measurement, the newmeasurement will replace the previously recorded value. The savedmeasurement can reuse the name assigned to the previously recorded valueit has replaced. If the name included an auto-increment number, thenewly recorded measurement will include the auto-increment number suchthat the auto-increment numbers in the sequence have an uninterruptedorder. Auto-incrementing numbers are discussed in further detail belowwith reference to FIGS. 9-16. Selecting Review 608 can allow a user toreview and optionally edit previously saved measurements. SelectingCancel 610 deactivates the autoSAVE function and deletes all previouslysaved measurements taken during the sequence.

FIG. 7 illustrates an example of a screen 700 that can appear afterReview 608 is selected in screen 600. As shown in FIG. 7, soft keyfunctions in screen 700 include Back 704, Forward 706, Replace 708, andClose 710. A relative sequence number 712 can be highlighted and/oraugmented with an indication of the total number of saved measurements714. Selecting Back 704 can change the screen to show the previousmeasurement in the sequence, if any. Selecting Forward 706 can changethe screen to show the next measurement in the sequence, if any.Relative sequence number 712 changes as the user scrolls back and forththrough the measurements to indicate which measurement in the sequenceis displayed. Measurements are preferably saved with a time stamp.

FIG. 8 illustrates an example of a screen 800 that can appear afterReplace 708 is selected in screen 700. As shown in FIG. 8, soft keyfunctions in screen 800 include Save 804, Redo From 806, and Cancel 808.Relative sequence number 812 can blink after Replace 708 is selected.Once multimeter 100 detects a new stable measurement, this value willreplace the previously recorded value. The saved measurement can reusethe name assigned to the previously recorded value it has replaced. Ifthe name included an auto-increment number, the newly recordedmeasurement will include the auto-increment number such that theauto-increment numbers in the sequence have an uninterrupted order.Auto-incrementing numbers are discussed in detail below with referenceto FIGS. 9-16.

In screen 800, selecting Save 804 saves the displayed value, rather thanthe next stable value, over the previous value at the currentlydisplayed relative sequence number 812. Pressing dedicated [HOLD] button125 performs the same function as Save 804 in screen 800. Selecting RedoFrom 806 can cause all of the measurements with higher relative sequencenumbers in the sequence to be discarded and for multimeter 100 to resumesaving from this relative sequence number as if it were now the last inthe sequence. In other words, the user can back up to a previous pointin the sequence of measurements and resume the sequence from that pointsuch that the new automatically saved measurements overwrite thosepreviously saved in the same positions in the sequence.

Once the user has selected Redo From 806, a message can be displayedrequesting the user to confirm that the redo function is being selectedto prevent accidental loss of measurements. If the user confirms theoperation, the multimeter saves the measurement over the previous valuewhich now becomes the last relative sequence number of the sequence.Then, the screen will return to the screen shown after the autoSAVEfunction was selected and the autoSAVE function will continue savingstable measurements.

Auto-Incrementing Numbers

When a user saves a current reading, the display may list various namesunder which the user can save the reading. Naming saved readings helpsthe user identify what the reading signifies, e.g., what the multimeterwas measuring, or the location where the reading was taken. The user mayselect one of the names or edit one of the names to suit the user'sneeds. If multimeter 100 is recording a series of readings sequentiallyin a single location, it is beneficial to have some way to distinguishbetween readings and to identify the order of the readings. Multimeter100 may include an auto-incrementing number function that automaticallyassigns numbers to sequential readings under a single name.

An example of the auto-incrementing number procedure is shown in FIGS.9-16. FIG. 9 shows a screen 900 displaying a live reading 902. As shownin FIG. 9, a soft key function in screen 900 can include Save 904. FIG.10 shows a screen 1000 after a user has selected Save 902 in screen 900.The filled in square 1102 next to Save denotes that the save function isselected from the menu. FIG. 11 shows a screen 1100 providing a list ofnames after the user has selected +Name 1004 in FIG. 10, which is thesame layout of the screen displayed after a user selects +Name 504 inFIG. 5. The first three names in the left hand column of the listinclude auto-incrementing numbers. The filled in square 1102 next toRoom-1 1002 denotes that the name Room-1 is selected. FIG. 12 shows ascreen 1200 after the user has selected Save 1104 using a soft key inFIG. 11. Message 1202 informs the user that the measurement is beingsaved as Room-1. FIG. 13 shows a screen 1300 after the measurement hasbeen saved and the display has returned to the VAC measurement screen.If the user decides to save another reading, the user may press the Savesoft key twice, which can bypass the menu of names shown in FIG. 11 andimmediately save the reading with the last name that was selected.

FIG. 14 shows a screen 1400 when the next reading 1402, which has thesame value as the first reading 902, is being saved. FIG. 15 shows ascreen 1500, which can appear after two readings have been recordedunder the name Room. At this point, Room-3 1504 is listed in the menu ofnames, since there are already two readings recorded under the nameRoom. If the user selects Reset-# 1504 while Room-3 1502 is selected inthe screen of FIG. 15, the auto-incrementing number in the selected namecan be reset to 1. FIG. 16 illustrates the menu of names after Reset-#1504 has been selected in screen 1500. Room-1 1602 is listed in the menuof screen 1600 instead of Room-3 1504.

Meter 100 may have a default of pre-defined names. For instance, FIG. 11illustrates a menu of eight pre-defined names. However, the user mayedit these names or input more names on a computer and download theadditional names to multimeter 100. FIG. 17 shows a screen displaying anexample character palette that may be used to edit names from the menuof names. The user can use navigation buttons 114-117 to highlightcharacters. Then, the user may press the soft key corresponding toSelect to select the highlighted character. Auto-# 1702 may behighlighted using the navigation buttons 114-117 and selected bypressing the soft key corresponding to Select 1704 to append anauto-incrementing number to a name. If the user elects not to useauto-incrementing numbers, a time stamp attached to each measurement candistinguish the measurements from one another. However, the time stampsmay be out of order when the user replaces measurements within thesequence after utilizing the autoSAVE Replace function in FIGS. 7 and 8.In this situation, the auto-incrementing numbers can facilitateidentification of the measurements.

Min/Max Background Recording

Min/Max is a mode in which the multimeter displays the live minimum,maximum, and average measurements that have occurred from the time theinitial measurement of a parameter have begun. In other words, whenevera new maximum or minimum occurs (i.e., exceeding the previous maximum orminimum), the new value is stored, and the respective elapsed time isupdated. The multimeter can give output, such as beeping, whenever a newminimum or maximum measurement occurs. Min/Max mode can be activated bythe user pressing [MIN MAX] 126 in the embodiment shown in FIG. 1.

Recording is the saving of a sequence of measurements for future reviewor storage. In some embodiments, the multimeter will begin recordingautomatically during min/max mode. The multimeter can record eachminimum, maximum, and average recordings at certain intervals of time.The multimeter can additionally record measurements when a predeterminedevent, such as the measurement value crossing an event recordingthreshold, has occurred.

Adjustment Threshold

Multimeter 100 may be configured to automatically record measurementsthat exceed a predetermined threshold or that deviate from baselinereadings by a predetermined threshold. The threshold may be measured ina variety of ways, including, e.g., an absolute number, a relativenumber, or a percentage. As an example of a percentage, the thresholdcould be measured relative to a previous reading; if multimeter 100detects that a measurement varies from the previous reading by a certainthreshold amount—for example, 4%—then multimeter 100 could automaticallyrecord the measurement. Multimeter 100 may include an interface formodifying the threshold value.

FIGS. 18 and 19 illustrate an example of a procedure that can be used tomodify the threshold value. FIG. 18 illustrates an example screen 1800having a menu for modifying the threshold for the autohold and eventrecording functions. In FIG. 18, the filled in square 1802 next to EventThreshold for AutoHold can denote that the threshold for autohold hasbeen selected. The open square 1804 next to Event Threshold forRecording can denote that the threshold for event recording has not beenselected. In some embodiments, the user may use navigation buttons114-117 to select which function on the menu to modify. By selectingEdit 1806, which can be done by pressing soft key 110, screen 1800 canchange to screen 1900, which is shown in FIG. 19 and in which the valueof the event recording threshold can be changed.

The “4” in 04% next to Event Threshold for Recording is highlighted inFIG. 19, which means that the user can change the value. Arrows 1902 canbe provided to notify the user that the up and down navigation buttonscan be used to change the value of the event recording threshold. Oncethe event recording threshold value has been altered within the display,the processor uses the new threshold value to determine whethermeasurements are stable when the event recording function is used.Likewise, when the autohold threshold value has been modified, theprocessor uses the new threshold value to determine whether measurementsare stable when the autohold function is used.

Easy Recording

Easy recording is a feature that allows a user to record one or both ofevent recording or interval recording by prompting the multimeter oncewithout the user having to configure parameters, such as recordingduration or a sample interval. Interval records are captured when thetime to store a measurement value, as designated by the recording sampleinterval (how often the measurement is recorded), has arrived. The usercan set the duration and sample interval for interval recording. Byusing easy recording, the user can prompt the multimeter to record, andthe processor will automatically begin recording with a sample intervalchosen by the processor. Rather than having a predetermined duration,easy recording can continue until a user prompts the multimeter to stoprecording, the memory runs out of room, or the multimeter loses power.As the memory fills and time passes during recording, the processor candown-sample recordings to make more space for future recordings and theprocessor can begin to record with a larger interval sample, which willdecrease the amount of memory necessary to continue recording. Theprocessor can be programmed to down-sample sampled data to reduce itssize and change the interval sample in response to a variety ofconditions, such as a certain amount of time passed and/or a certainamount of remaining memory. Events can be preserved during down-samplingso that meaningful data is not lost.

Battery Saver Mode

To conserve energy, multimeter 100 can include a battery saver mode,which is particularly useful when the multimeter is recording for longperiods of time without any user interaction. FIG. 20 illustrates anexample configuration of processors that facilitates battery saver mode.A measurement processor 2000 is connected to an application processor2002, which is connected to a main memory 2004. Measurement processor2000 can be programmed to take raw, live measurements. Applicationprocessor 2002 can be programmed to perform other functions, includingsaving measurements to main memory 2004 or changing the range ofmeasurements.

The battery saver mode can be activated in response to a variety ofconditions, such as a user input or the passage of a certain amount oftime without any user input. During the battery saver mode, display 105can be turned off and application processor 2002 can operate at areduced clock speed (or alternatively, put into hibernate mode where oneor more of its clocks are powered down) to achieve minimal power usewhile measurement processor 2000 continues to acquire and buffer data.When a predetermined number of results are buffered, or a period of timeelapses, measurement processor 2000 may activate the applicationprocessor 2002. Thereafter, application processor 2002 may resumeoperation at its normal clock speed, data can be retrieved frommeasurement processor 2000, processed and recorded, and the clock speedof application processor 2002 can be reduced again. During the batterysaver mode, application processor 2002 remains relatively or completelyidle most of the time, only running in short bursts to process recentmeasurement data. The semi-autonomous running of measurement processor2000 combined with partial (or complete) suspension of applicationprocessor 2002 can extend battery life.

As shown in FIG. 1, On/Off button 118 can include a blinking LED forindicating when multimeter 100 is in battery saver mode. Multimeter 100can be programmed to beep or otherwise indicate when battery saver modeends and/or begins. The battery saver mode can be ended in response to avariety of conditions, such as direct user input to end battery savermode or a user simply beginning to interact with the multimeter.Measurement processor 2000 may be implemented by any of severalwell-known technologies. For instance, in some embodiments, measurementprocessor 2000 comprises an ultra-low-power microcontroller such as theTexas Instruments MSP430. Similarly, application processor 2002 may beimplemented by any of several well-known technologies. For instance, insome embodiments, application processor 2002 is implemented by aFreescale I.MXS MC9328, which is a microcontroller built around an ARM9core.

CONCLUSION

In various embodiments, the features discussed above can be provided invarious combinations or sub-combinations within a single multimeter. Forexample, in some embodiments, the AutoSAVE function and theauto-incrementing number function can be used in combination so that themultimeter automatically saves a sequence of stable measurements withauto-incrementing number function can be used in combination so that themultimeter automatically saves a sequence of stable measurements withauto-incrementing numbers attached to the name of each measurement inthe sequence. In other embodiments, the features may be providedseparately.

Specific details of the disclosed embodiments of the invention are setforth in the description and in the figures to provide a thoroughunderstanding of these embodiments. A person skilled in the art,however, will understand that the invention may be practiced withoutseveral of these details or additional details can be added to theinvention. Well-known structures and functions have not been shown ordescribed in detail to avoid unnecessarily obscuring the description ofthe embodiments of the invention.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense ofincluding, but not limited to. Additionally, the words “herein”,“above”, “below”, and words of similar connotation, when used in thisapplication, shall refer to this application as a whole and not to anyparticular portions of this application. Where the context permits,words in the above Detailed Description using the singular or pluralnumber may also include the plural or singular number respectively. Theword “or”, in reference to a list of two or more items, covers all ofthe following interpretations of the word: any of the items in the list,all of the items in the list, and any combination of the items in thelist.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize.

The teachings of the invention provided herein can be applied to systemsother than the multimeters described above. The features of the variousembodiments described above can be combined or altered to providefurther embodiments.

These and other changes can be made to the invention in light of theabove Detailed Description. While the above description describescertain embodiments of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the describedembodiments may vary considerably in their implementation details, whilestill being encompassed by the invention disclosed herein.

The terminology used in the Detailed Description is intended to beinterpreted in its broadest reasonable manner, even though it is beingused in conjunction with a detailed description of certain specificembodiments of the invention. Certain terms may even be emphasized;however, any terminology intended to be interpreted in any restrictedmanner will be overtly and specifically defined as such in this DetailedDescription section. In general, the terms used in the following claimsshould not be construed to limit the invention to the specificembodiments disclosed in the specification, unless the above DetailedDescription section explicitly defines such terms. Accordingly, theactual scope of the invention encompasses not only the disclosedembodiments, but also all equivalent ways of practicing or implementingthe invention under the claims.

While certain aspects of the invention are presented below in certainclaim forms, the inventors contemplate the various aspects of theinvention in any number of claim forms. Accordingly, the inventorsreserve the right to add additional claims after filing the applicationto pursue such additional claim forms for other aspects of theinvention.

1. A digital multimeter, comprising: a measurement component forreceiving measurement data corresponding to one or more physical orelectrical parameters; a user interface component for receiving userinput to save measurement data and associate one or more names with thesaved data; and an auto-incrementing descriptor component forautomatically assigning incremented descriptors to the saved data. 2.The digital multimeter of claim 1, wherein the saved data comprises afirst data reading associated with a name and a first automaticallyincremented descriptor; and a second data reading associated with thename and a second automatically incremented descriptor; wherein theautomatically incremented descriptors indicate the order in which thesaved data was received.
 3. The digital multimeter of claim 1, whereineach name comprises a string of alphanumeric characters and anautomatically incremented descriptor appended to the string ofalphanumeric characters.
 4. The digital multimeter of claim 1, whereinat least one of the automatically incremented descriptors comprises anumber.
 5. The digital multimeter of claim 1, wherein at least one ofthe automatically incremented descriptors comprises a letter.
 6. Thedigital multimeter of claim 1, further comprising: a sequence recordingcomponent for saving a sequence of readings in response to a single userinput presented at the user input component; wherein the multimeterassociates each reading among the sequence of readings with a name andthe auto-incrementing component automatically assigns an automaticallyincremented descriptor to each name associated with the sequence ofreadings.
 7. The digital multimeter of claim 1, wherein the userinterface component comprises; a display screen; and a plurality of softbuttons each having a function indicated by one or more correspondingdisplay elements presented on the display screen.
 8. The digitalmultimeter of claim 1, wherein the names are generated from a set ofdefault names stored in a memory within the digital multimeter or amemory attached to the digital multimeter.
 9. The digital multimeter ofclaim 8, further comprising an editing component allowing a user to editthe default names via the user interface component.
 10. The digitalmultimeter of claim 1, wherein the auto-incrementing descriptorcomprises a time and date indicating when the measurement data wasobtained.
 11. The digital multimeter of claim 1, further comprising: areset component for resetting values of the automatically incrementeddescriptors in response to one or more user inputs.
 12. The digitalmultimeter of claim 1, wherein the measurement component comprises oneor more probes operatively connected to a measurement processor.
 13. Thedigital multimeter of claim 1, wherein each of the names indicates alocation where the measurement data was obtained or a type ofmeasurement represented by the measurement data.
 14. A method of storinga plurality of readings in a digital multimeter comprising a measurementcomponent, a data storage component, and an auto-incrementing descriptorcomponent, the method comprising: receiving through the measurementcomponent measurement data corresponding to one or more physical orelectrical parameters; storing in the data storage component a firstreading of the measurement data and a first name associated with thefirst reading, wherein the first name includes a first descriptor; byoperation of the auto-incrementing descriptor component, automaticallyincrementing the first descriptor to generate a second descriptor;storing in the data storage component a second reading of themeasurement data and a second name associated with the second reading,wherein the second name includes the second descriptor.
 15. The methodof claim 14, wherein the digital multimeter further comprises a displaycomponent and a user input component, the method further comprising:displaying on the display component the first auto-incrementeddescriptor and a default name for the first reading; receiving selectioninput of the default name via the user input component; and in responseto the selection input, appending the first descriptor to the defaultname to generate the first name and storing the first name in the datastorage component.
 16. The method of claim 14, wherein the digitalmultimeter further comprises a display component and a user inputcomponent, the method further comprising: displaying on the displaycomponent the first auto-incremented descriptor and a prompt for a userto enter an alphanumeric string for the first name; receiving via theuser input component a user-entered alphanumeric string; appending thefirst descriptor to the user-entered alphanumeric string to generate thefirst name and storing the first name in the data storage component. 17.The method of claim 14, wherein the first and second names indicate anorder in which the first and second readings occurred.
 18. The method ofclaim 14, wherein the first name indicates a location where the firstreading occurred and the second name indicates a location where thesecond reading occurred.
 19. A method of operating a digital multimetercomprising a display component, a user input component, and a datastorage component, the method comprising: displaying a first screen onthe display component, the first screen showing: a first, selectedmeasurement reading among a sequence of measurement readings stored inthe data storage component, wherein each measurement reading in thesequence corresponds to a measurement of a physical or electricalparameter; a current descriptor indicating a relative position of theselected measurement reading within the sequence; and a plurality ofsoft key labels corresponding to respective soft keys of the user inputcomponent; receiving user input via a soft key; and in response to theuser input, displaying on the display component a second screen showing:a second measurement reading among the sequence of measurement readings;and a second descriptor indicating a relative position of the secondmeasurement reading within the sequence in relation to the firstmeasurement reading; wherein the first and second descriptors aregenerated automatically based on an order in which the first and secondmeasurement readings were obtained.
 20. The method of claim 19, whereinthe first and second descriptors comprise a number.